jtulach@26: package api;
jtulach@26: 
jtulach@210: import java.util.ArrayList;
jtulach@26: import java.util.Collection;
jtulach@210: import java.util.Collections;
jtulach@210: import java.util.HashSet;
jtulach@210: import java.util.Iterator;
jtulach@210: import java.util.List;
jtulach@26: import java.util.Set;
jtulach@26: 
jtulach@26: /** Simplified version of NetBeans 
jtulach@26:  * <a href="http://bits.netbeans.org/6.0/javadoc/org-openide-util/org/openide/util/Lookup.html">Lookup</a>
jtulach@26:  * reimplemented to separate the API for clients
jtulach@26:  * from the API for implementators while guaranteeing
jtulach@26:  * consistency among all there methods.
jtulach@26:  *
jtulach@26:  * @author Jaroslav Tulach <jtulach@netbeans.org>
jtulach@26:  * @version 2.0
jtulach@26:  */
jtulach@26: // BEGIN: design.consistency.2.0
jtulach@210: public abstract class Lookup {
jtulach@210:     /** only for classes in the same package */
jtulach@26:     Lookup() {
jtulach@26:     }
jtulach@26:     
jtulach@26:     // BEGIN: design.consistency.lookup.2.0
jtulach@26:     public <T> T lookup(Class<T> clazz) {
jtulach@210:         Iterator<T> it = doLookup(clazz);
jtulach@210:         return it.hasNext() ? it.next() : null;
jtulach@26:     }
jtulach@26:     // END: design.consistency.lookup.2.0
jtulach@26: 
jtulach@26:     // BEGIN: design.consistency.lookupAll.2.0
jtulach@26:     public <T> Collection<? extends T> lookupAll(Class<T> clazz) {
jtulach@210:         Iterator<T> it = doLookup(clazz);
jtulach@210:         if (!it.hasNext()) {
jtulach@210:             return Collections.emptyList();
jtulach@210:         } else {
jtulach@210:             List<T> result = new ArrayList<T>();
jtulach@210:             while (it.hasNext()) {
jtulach@210:                 result.add(it.next());
jtulach@210:             }
jtulach@210:             return result;
jtulach@210:         }
jtulach@26:     }
jtulach@26:     // END: design.consistency.lookupAll.2.0
jtulach@26: 
jtulach@26:     // BEGIN: design.consistency.lookupAllClasses.2.0
jtulach@26:     public <T> Set<Class<? extends T>> lookupAllClasses(Class<T> clazz) {
jtulach@210:         Iterator<T> it = doLookup(clazz);
jtulach@210:         if (!it.hasNext()) {
jtulach@210:             return Collections.emptySet();
jtulach@210:         } else {
jtulach@210:             Set<Class<? extends T>> result = 
jtulach@210:                 new HashSet<Class<? extends T>>();
jtulach@210:             while (it.hasNext()) {
jtulach@210:                 result.add(it.next().getClass().asSubclass(clazz));
jtulach@210:             }
jtulach@210:             return result;
jtulach@210:         }
jtulach@26:     }
jtulach@26:     // END: design.consistency.lookupAllClasses.2.0
jtulach@210: // FINISH: design.consistency.2.0
jtulach@210:     
jtulach@210:     abstract <T> Iterator<T> doLookup(Class<T> clazz);
jtulach@26: }